How to not be so terrified of sids?

My lo just turned 4 months old. My husband and I have been taking shifts watching her since she was born so someone is always awake with her even when she is sleeping. I know that might sound crazy but I am just so terrified to have us sleep when she does. I know it's getting hard for my husband as he works as well and to be honest it can be tiring for me too. I just don't know how I can do it. Any advice is helpful as I know we can't do this forever lol